Ellipsograph



(No Model.)

A. W. LEIGHTON.

ELLIPSOGRAPH. No. 426,288. Patented Apr. 22,1890.

Nrrn STATES PATENT OFFICE.

ALTON \V. LEIGIITON, OF NEIV HAVEN, CONNECTICUT.

ELLIPSOGRAPH.

SPECIFICATION forming part of Letters Patent No. 426,288, dated April 22, 1890.

Application filed January 17, 1890. Serial No. 337,257. (No model.)

To all whom it may concern:

Be it known that I, ALTON IV. LEIGHTON, a citizen of the United States, residing at New Haven, in the county of New Haven and State of Connecticut, have invented new and useful Improvements in Ellipsographs, of which the following is a specification.

My invention relates to ellipsographs; and my improvements therein consist in providing the needle-bars of instruments used for drawing circles with an interior axial or oblique eye or bore for receiving and confining the thread or cord in position centrally, or substantiallyso, with the needle-point, whereby the thread is inclosed within the needlebar itself in position to be delivered therefrom directly at the side of the point which pierces the paper, so that approximately perfect accuracy is obtained in drawing ellipses. This construction gives the advantage of confining the thread at the base of the needlebar and of holding it directly upon the paper under the end of said bar. It gives the advantage of adapting the double needle-bar employed in dividers and beam-compasses for drawing circles, as a means of usinga thread or cord for drawing ellipses, and thereby dispenses with the use of separate instruments as ellipsographs.

My improvement also gives the advantage of using a cord, which is held at the piercingpoint of one of the needle-bars, and, passing upward through the bore of the other needlebar at the side of its pielcingpoint, may be held by the fingers of the hand holding the instrument, and thereby render it easy and convenient in applying and adjusting and holding or securing the thread to suit the size of the ellipse to be drawn.

The accompanying drawings illustrate my improvement as applied to a pair of dividers, in which- Figure 1 is a view in perspective, showing the manner of using my invention in a pair of dividers. Fig. 2 is an elevation of the dividers containing my improvement. Fig. 3 shows, on an enlarged scale, one of the detachable divider-legs with my improvement applied thereto. Fig. 4 shows, on an enlarged scale, the doubleneedle-bar in section, showing my improvement; and Fig. 5 is a perspective view of the double needle-bar provided with the longitudinal bore for the thread.

The needle-bars a a are made double-ended, with points of any preferred form, or such as is used in dividers. Only one end of each of these bars, however, is provided with my improvement, and for that purpose I prefer to terminate it in a flat end Z) at right angles to the axis of the bar, and to provide such end with a central pin or needle-point c, at the side of which the bore emerges.

The divider-legs are constructed in the usual manner for receiving and clamping the separate needle-bars, and for that purpose the legs are split and provided with the usual clamp-screw i.

That end of each needle-bar which terminates in a flat end has an axial or oblique bore f, which opens at said flat end at the side of the needle-point 0, while the other end of the bore or eye opens at (Z at the side of the bar a short distance above the point. In order that this bore shall be substantially in central or axial relation to the bar, the latter may be notched or filed away at e at the side about equal to half the thickness of the bar, so that the bore opens at the bottom of this notch at or quite near the axis of the bar. The bore, however, may stand oblique to the axis of the needle-bar and made without the side notch in the latter, and in such case I prefer to make the end of the needle-bar terminate in a conical point.

I prefer to use a thread or cord g, braided from threads to form what 'is called surgeons twisted silk ligature to insure strength, inelastieity, and prevent raveling, and in using such thread itis inserted through the bore of one needle-bar and secured thereto by a knot 71, while the other end is drawn up through the other bore and held by the hand which holds the instrument, and is conveniently adjusted to give the desired size or ellipse. The thread is thus held within the body of each needle-bar, so that the fiat ends of the latter may rest directly upon the thread at the needles, so that the thread lies upon the paper at the points of foci.

In describing an ellipse the needle-points are pinned in the paper at the centers of the ellipse to be drawn, and the thread may be drawn up into the recess at the joint or head of the dividers and held by the thumb and forefinger of the hand which holds the dividers. The point of the pencili or pen is then placed against the thread between the needlepoints and the thread drawn out to the proper slack from that point, through which it passes to the hand, and from which it is allowed to slide until the point of the pencil reaches the end of the short axis of the ellipse, when the thread is clamped and held by the fingers. The pencil or pen is now moved to the extremity of the slack of the thread and will describe the ellipse around the two foci or needle-points.

The eye or bore may be of any desired shape, provided it leads to and holds the thread in a position actually or approximately coincident with the focus of the ellipse.

While I have shown the free end of the thread as being held by the hand when adjusted, yet it is obvious that this end of the thread may be secured or held by winding it around the thumb-screws or other projecting points of the dividers.

I claim as my improvement 1. I11 an instrument for drawing circles, the needle-bars formed each with a longitudinal bore or eye opening at one end of the bar at the side of the needle and at the side of the bar above said end, substantially as described, for the purpose specified.

2. In an instrument for drawing circles, the needle-bars formed with a longitudinal bore or eye opening at one end of the bar and formed with a notch or' recess in its side at which the said bore terminates above said end, substantially as described.

3. In an instrument for drawing circles pro- Vided with clamping-sockets, needle-bars formed with points at each end and with an eye or bore opening at one end of the said bar and at the side above said end, substantially as described.

4. In an instrument for drawing circles, needle-bars for the same, each formed with a bore which opens at the end and at the side of said bar above its end, and a thread or cord passed through said bores and secured. in one of them, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

ALTON \V. Ll-LIGHTON.

\Vitnesses:

JULIUS TWISS, \V. A. BEERs. 

